I had an error similar to this and it seems to have been solved by moving the Notepad++ plugins folder to Windows\SysWOW64 (I created a Notepad++ folder for it there, for clarity). I’m setting up all my tools on a new Windows 10 laptop and this worked for another dll I had trouble with already. I also made copies of stylers.xml, config.xml and langs.xml from the stylers.model.xml etc supplied. This may only have been necessary due to not running as Administrator during setup. I installed from the zip file, rather than the installer, which maybe would have taken care of all these things.